Which category of hair products is effective in reducing static electricity?

Anti-frizz serums are specifically formulated to combat frizz and static electricity in hair. These serums typically contain silicone or other smoothing ingredients that help to create a barrier around the hair shaft, sealing in moisture and reducing the likelihood of frizz caused by humidity or dry air. This barrier also helps to reduce static electricity, which can occur when hair becomes dry or when it rubs against clothing or other surfaces.

In contrast, hair mousses primarily add volume and hold to styled hair but do not focus on reducing static. Hair sprays are used to set styles and may help with hold but are not specifically designed to combat static. Leave-in conditioners provide moisture and can help with detangling but may not have the targeted properties needed to effectively reduce static electricity like anti-frizz serums do. Thus, anti-frizz serums stand out as the most effective choice for addressing static in hair.